The Halachos are based on the rulings of the Mishna Berura (MB) and Shmiras Shabbos Kehilchasa (SSK), reflecting Ashkenazi practice
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Torah Prohibition of Writing
- The Torah melacha of ‘kosev’ (or ‘koseiv’) writing, on Shabbos, entails writing with a substance which leaves a permanent mark, such as ink, lead etc, on a permanent surface such as paper, parchment etc
Writing on One’s Skin
- It is a Torah prohibition to write on one’s skin with a pen etc – even though the writing will not last indefinitely, this is as it gets ‘rubbed off’ by sweat etc, not because the writing itself wasn’t done in a permanent way (MB 340:22).
Rabbinic Prohibition
- It remains forbidden to write on Shabbos on a Rabbinic level even if:
- One writes with a substance which will not last permanently, such as fruit juice
- One writes on a surface which will not last permanently, such as on leaves, dust or sand.
- It is a Rabbinic prohibition to write even if both the above apply, ie one is writing with a non-permanent substance on a non-permanent surface (SA 340:4, MB 18, 19, 22)
Dominant vs Non-Dominant Hand
- It is only a Torah prohibition of kosev on Shabbos if one writes with one’s dominant hand; however, if one writes with one’s non-dominant, weaker, hand, such as a right-handed person who writes with their left hand, it is a Rabbinic prohibition. It is a Torah prohibition for one who is ambidextrous to write with either hand (MB 340:22)
Writing With One’s Finger
- It is also forbidden to write on Shabbos if one is not using a ‘substance’, but rather marks out letters with one’s finger or a utensil on a surface.
- Drawing in congealed fat: For example, it would be a Torah prohibition to etch letters with one’s finger on congealed fat (as it will last permanently on this surface)
- Drawing on a steamed-up window: And it is a Rabbinic prohibition to draw letters with one’s finger on a steamed-up window (as this will not last permanently). It is similarly forbidden to etch letters with one’s nail on paper (MB 340:20, 24, SSK 16:28).
- When no mark is left: However, it is permissible to draw letters in the air with one’s finger, or trace the shape of letters with one’s (clean) finger on a sheet of paper, given one is not making any kind of mark (R 340:4, MB 22).
Drawing Pictures
- It is also a Torah prohibition to draw pictures on Shabbos; this is a sub-category (tolda) of the melacha of ‘Kosev’, writing (MB 340:22).
Drawing Non-Descript Marks
- It is a Rabbinic prohibition to draw non-descript marks, lines etc on Shabbos. One may also not erase them (MB 340:42, 25, OS 15:6).
Erasing – Mochek
- The melacha of ‘mochek’, erasing on Shabbos, mirrors the melacha of Kosev – the Torah melacha can only apply if one erases writing or images made with a permanently lasting substance, from a surface which lasts permanently. It remains Rabbinically prohibited to erase writing even if the substance it was written with, or the surface it was written on are non-permanent (MB 340:22).
For a Constructive Purpose
- Furthermore, it is only a Torah prohibition if one is erasing for a constructive purpose, eg to write or draw other things in that space, or if there is an extra letter in a Sefer Torah and one is erasing it to make the Sefer Torah kosher, as an extra letter invalidates a Sefer Torah. Erasing in a non-constructive fashion is a Rabbinic prohibition.
Erasing Non-Descript Marks
- It is a Torah prohibition to erase even non-descript markings if one wishes to write in their space – this is one area where erasing is stricter than writing (we saw that making non-descript marks is only Rabbinically forbidden) (SA 340:3).
What Is Considered Erasing
- The melacha of erasing includes other ways of getting rid of words, images etc, not just erasing them – for example if one were to pour ink over the letters so they are no longer identifiable, or if one destroys the paper they are on, such as if one burns it (this can be relevant if one eg does a barbecue on Yom Tov – one shouldn’t use newspaper with writing on to fuel the fire) (OS 15:46).
